neo4j-uuid

warning: this project is pretty much outdated, I suggest to use the well maintained https://github.com/graphaware/neo4j-uuid instead.

purpose

A lot of Neo4j based projects I've seen need a unique identifier for nodes/relationship to reference contents in the graph database from some third party system. The most obvious thing namely using node.getId() is a bad choice since after deletion of a node its id might be recycled. For details on why and how this works, see an excellect blog post. A best practice for having unique identifiers is to assign each node/relationship a uuid property and let Neo4j perform autoindexing on the uuid property. Third party systems store only the UUID. A simple index lookup retrieves then the referenced node or relationship in the graph database.

license

GPL v3

build & install

neo4j-uuid uses Gradle as build system. To install uuid-neo4j in a Neo4j server instance:

• call ./gradlew assemble
• copy ./build/libs/neo4j-uuid.jar to your Neo4j server's plugins directory
• copy the latest version of http://mvnrepository.com/artifact/com.fasterxml.uuid/java-uuid-generator to Neo4j's plugins directory as well (will automate that step in future).

• amend $NEO4J_SERVER/conf/neo4j-server.properties with the following line:

  org.neo4j.server.thirdparty_jaxrs_classes=org.neo4j.extension.uuid=/db/uuid

implementation details

• for testing Spock is used
• Neo4j scans using JDK ServiceLoader for registered implementations of KernelExtensionFactory. We register UUIDKernelExtensionFactory that passes back an instance of UUIDLifeCycle. UUIDLifeCycle takes care of setting up auto indexing for uuid properties and registers a UUIDTransactionEventHandler
• a second component provides a unmanaged extension for querying nodes/rels by uuid, see UUIDRestInterface